OBJECTIVE: The purpose of this study was to investigate the feasibility of prospective ECG-triggered axial 64-MDCT angiography of the aorta and coronary arteries performed at a tube voltage of 100 kV. SUBJECTS AND METHODS: Thirty patients with a heart rate less than 75 beats/min who were referred for aortic CT angiography were enrolled. The image quality of the ascending aorta, aortic valve, and coronary arteries was evaluated for motion artifacts. Contrast enhancement (mean attenuation) was measured in the ascending aorta, descending aorta, and bifurcation of the aorta. Aortic valve and coronary artery lesions were surveyed. RESULTS: Acceptable image quality was achieved in 100% (30/30) of cases for the ascending aorta, 97% (29/30) of cases for the aortic valve, and 98% (442/452) of coronary arterial segments. Contrast enhancement was greater than 200 HU and was satisfactory (ascending aorta, 379 +/- 80 HU; descending aorta, 354 +/- 72 HU; bifurcation, 355 +/- 96 HU). Lesions found in the aortic valve were plaque (n = 16) and bicuspid valve (n = 1) and in the coronary arteries were > or = 50% luminal stenosis (n = 5), plaque (n = 21), myocardial bridge (n = 12), and anomalous origin (n = 1). The effective radiation dose was estimated to be 7.5 +/- 1.7 mSv. CONCLUSION: For patients with a heart rate less than 75 beats/min, prospective ECG-triggered axial CT angiography at a tube voltage of 100 kV has the potential to provide clinically relevant information about the aorta and coronary arteries with low radiation exposure.